1. Field of the Invention
The present invention relates to a semiconductor integrated circuit equipped with dynamic random access memories or the like for use in various appliances such as digital appliances.
2. Description of Related Art
A system LSI (large scale integrated circuit) is often used for digital appliances which have been experiencing fierce price competition. Accordingly, there is an increasing demand for reduction in chip cost and the number of pads used. However, in recent years, semiconductor devices have been fabricated at a finer pitch and the number of pads required for a semiconductor integrated circuit such as a system LSI is increasing due to increased scale of a logic circuit and the combination of analog circuits and memory circuits on a single chip.
Above all, the number of pads required for memory inspection is increasing because the capacity and the number of memories included in the system LSI are increasing with the improvement in function and performance of the digital appliances. Therefore, it is urgently required to reduce the number of the pads used for the memory inspection, such as pads for monitoring internal supply voltages delivered from internal power supply circuits to dynamic random access memories.
With respect to a semiconductor integrated circuit including a plurality of internal power supply circuits for delivering a power supply voltage to memories, Japanese Unexamined Patent Publication No. 2004-186435 discloses a technique of switching the conduction between the internal power supply circuits and a monitoring pad with use of a switch.
Further, according to Japanese Unexamined Patent Publication No. 2005-259267, an internal power supply voltage output by a single internal power supply circuit is shared among a plurality of memories to reduce the chip area.
In the semiconductor integrated circuit including a plurality of internal power supply circuits as described above, however the pads used for monitoring the power supply voltage or applying an external voltage are required for every internal voltage generator circuit, or alternatively, a switch is required as disclosed by Japanese Unexamined Patent Publication No. 2004-186435.